The present invention is directed generally to a new electrically controlled brake system for a tractor, the system including a manually actuatable anti-jackknifing brake that acts only on the brakes of a trailer connected to the tractor.
Brake systems with anti-jackknifing brakes are known. Anti-jackknifing brakes are used, for example, to maintain appropriate spacing on downhill grades between the tractor and the trailer in a vehicle train. Such anti-jackknifing brakes are also used advantageously on level driving surfaces. Further, anti-jackknifing brakes are useful for testing the braking effect of the trailer. Further still, the connection of the tractor to the trailer can also be tested with anti-jackknifing brakes.
In conventional brake systems with anti-jackknifing brakes, the service brake of the trailer is actuated via a manual lever in the vehicle operator's cab in order to brake only the trailer (the tractor is not braked during manual actuation of the lever). Such conventional anti-jackknifing brakes are, however, pneumatically actuated. For this purpose, the manual lever in the operator's cab is in pneumatic communication with the brake system. This is a disadvantage since compressed-air lines must be installed in the operator's cab, which therefore makes the brake system more expensive. Also, more stringent safety requirements must be satisfied when compressed-air lines are routed in an operator's cab, also contributing to the greater cost. Furthermore, the routing of compressed-air lines in an operator's cab imposes a considerable demand for space in the cab, at the expense of the operator's comfort.
It is, accordingly, desired to provide an improved brake system with an anti-jackknifing brake function.